In telecommunications, the term asymmetric communication link refers to a communication link in which the data speed or quantity differs in one direction as compared with the other direction. Asymmetric data flow can, in some instances, make more efficient use of the available resources than symmetric data flow, in which the speed or quantity of data is the same in both directions. Asymmetric Digital Subscriber Line (ADSL) is an example of asymmetric communication link. Complete theoretical descriptions, details, explanations, examples, and applications of these, and related subjects and phenomena are readily available in standard references in the field of communications.